Download experimental study regarding changes of medio

THE PUBLISHING HOUSE
OF THE ROMANIANACADEMY
MEDICINE
Research article
EXPERIMENTAL STUDY REGARDING CHANGES OF MEDIO-SAGITTAL SUTURE
POST-DISJUNCTION ON COMMON BREED RABBIT
Ruxandra BARTOK1 , Constantin VARLAN1, Radu STANCIU1, Bogdan DIMITRIU1,
Oana AMZA1, Ileana SUCIU1, Sanziana SCARLATESCU1, Irina GHEORGHIU1, and Ioana SUCIU1
1
“Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
E-mail: [email protected]
Accepted January 16, 2015
Intermaxillary disjunction is defined as the release of medio-palatine suture using mechanical
forces. The role of this procedure is to expand the upper jaw in order to achieve the broadening of
the upper arch. The present paper is an experimental research on regarding medio-sagittal suture post
disjunction in order to study the bone changes which are taking place as a result of the split of
median maxillary suture. The disjunctors were applied on laboratory animals, activated in one
sitting. Radiological estimates pre- and post-disjunction and also, CT evaluation was carried out in
two points, namely, at the end of the active phase of expansion and after contention. The results
demonstrates that the therapeutic method induces permanent stuctural bone changes, offering an
additional guarantee as in terms of maintaining the stability of the orthodontic treatment outcome, but
further studies have to be done as the animal laboratory testing findings are not directly transferable
to human tissue.
Keywords: intermaxilary disjunction; medio-palatine suture; maxilar bone; ortodontic treatment.
INTRODUCTION1
Expanding the upper jaw by releasing median
suture is a relatively common clinical
procedure. This research has proposed, on a
common strain of rabbit breed, a study on bone
changes produced by the split of median maxillary
suture in an attempt to emphasize that the purpose
of this therapeutic technique is to obtain additional
bone. Of course, changes on rabbit desmal tissue
can not be treated as an overall human ones.
Intermaxillary disjunction is defined as the
release of medio-palatine suture using an
orthopedic forces. Thus, the yield is expansion of
the upper jaw transversely. According to Boboc 16
“intermaxillary disjunction offers the possibility
that in a short time to achieve considerable
broadening of the upper arch, hard palate, nasal
and even the face.”
MATERIAL AND METHODS
The disjunction technique requires two essential
characteristics, i.e. a firm anchorage on the sides
1
Proc. Rom. Acad., Series B, 2015, 17(2), p. 111–115
and using a device that can cope with the
disjunction separating effort on medio-sagittal
suture7,8.
Therefore, there were developed two metal
trays to size rodent’s side areas, on a dry skull,
allowing, on the one hand, getting a model easy to
use and fingerprinting to build the disjunctor.
Given that the experiment rabbits were part of
the same strain, individual modifications of the
lateral sides proved minimal (common breeds
rabbits had an average weight of about 2700 g). In
order to individualize the contact between the
metal trays and the dental sector, there have been
practiced retentions in trays, which were fixed to
the sides by means of a self-curing material. Thus,
the developed devices have been used throughout
the batch of studied rabbits and in some cases
reused on experimental animals.
It was used a Dentaurum screw type for
disjunction, with parallel outlets, whose arms were
welded to the metal trays (Fig. 1).
Thereafter, radiological estimates pre- and postdisjunction were obtained, at the same time
intervals at which measurements were performed
on the width of the base jaws, using computerized
tomography, measuring the upper intermolar
distanceof the first maxillary molar.
112
Ruxandra Bartok et al.
On 9 rabbits the disjunctors were cemented on
the premolars and molars of the upper arch, on
each side of the center line, with a self-curing
material (Structur 2, Voco, Germany).
The disjunctors were then activated in one
sitting (rapid maxillary expander) (Fig. 3). The
first group of rabbits was euthanized immediately
after setting and activating the devices, using
general anesthesia was practiced neuroleptanalgesia with Acepromazine 0.4 mg/kg body
and Ketamine 0.5 mg/kg body, the second group
after 7 days, and the third one after 14 days.
Fig. 1. The disjunctor – using a Dentaurum screw type, whose
arms were welded to the metal trays.
In agreement with previous studies 5,9,11 our
determinations on the bone post-disjunction effects
showed similar results.
The disjunctors were applied to a total of 9
rabbits (using groups of 3 rabbits) (Figs. 2, 3).
RESULTS AND DISCUSSION
It was found that the orthopedic forces
developed by the disjunction device produced the
split of the medio-sagittal suture, which caused the
onset of a process of tissue repair 5,12 and finally
the formation of new bone.
The osteo-forming activity is predominant,
following the osteoclasts wave, with dense
mesenchymal tissue4,6 and with the presence of
very active osteoblasts, in contact with lamellar
bone on which primitive bone is formed, due to
microfracture that occurred after traction (Fig. 4).
Fig. 2. After applying the disjunctor.
Fig. 4. Predominantly osteo-forming activity with the presence
of mesenchymal tissue
and osteoblasts adjacent to lamellar bone.
Fig. 3. Activating the disjunctor.
The next image presents a net tendency to
suture closure by new bone tissueforming
Experimental study regarding changes of medio-sagittal suture post-disjunction on common breed rabbit
(Fig. 5). It signals the presence of immature
nonlamellar bone crack on lateral slopes and the
presence of osteocytes in mature lamellar bone.
Fig. 5. Closing of the crack trend on median suture
surrounding, throughout the ossification process.
113
Most studies indicate that the newly formed bone
require longer periods of consolidation1,2,9,11. After
consolidation, which can be considered as early as
2 weeks up to 3 months after disjunction, were
recorded the best results on animal models, without
the regenerated bone to evidence (in a qualitatively
or quantitatively manner) characters of a normal
bone, under the conditions that bone remodeling
may take up to a year or more.
In this study we demonstrated and objectified
the fact that the split of the medio- palatine suture
on experimental animal is possible on “in vivo”
system, interpreting the bone and cartilage cell
response to mechanical force. Thus, the expansion
force acting along the suture, induced bone
resorption by activation of the osteoblast, as well
as by formation of new bone, due to the
proliferation and differentiation of periosteal cells.
There have been recorded pre- disjunction
(Fig. 6) and post-disjunction (Figs. 7, 8) radiological estimates at the same time intervals at which
there have been made histological estimates, as well.
Fig. 6. Axial and lateral angulation – radiographic image obtained before the disjunction.
Fig. 7. Axial and lateral angulation – radiographic image obtained at the end of the active phase of expansion
(with modified disjunctor).
114
Ruxandra Bartok et al.
Fig. 8. X-ray image obtained after disjunction (lateral and axial view).
Fig. 9. CT images recorded on day 14 after disjunction: suggestive appearance of medio-sagittal suture separation.
Fig. 10. CT images recorded at an interval of three weeks after contention.
At 14 days after rapid disjunction, on axial
angulation radiography (Fig. 8), a dehiscent area is
recorded, corresponding to the separation of the
maxillary bones.
CT evaluation of the effects on the bone
structure caused by rapid disjunction was carried
out in two points, namely, at the end of the active
phase of expansion (Figs. 9, 10) and a three- week
interval after contention.
Therefore, Figure 9 shows medio-sagittal suture
separation, which is more obvious in the anterior
segment of the palate. The images obtained from
CT (Fig. 10), after three weeks of contention, new
bone formation was observed with obvious
tendency to maintain the result obtained after rapid
disjunction.
CONCLUSIONS
1. The newly formed bone represents a favorable
substrate for tooth movement, allowing
Experimental study regarding changes of medio-sagittal suture post-disjunction on common breed rabbit
apposition and resorption process development,
the cornerstone of any fixed orthodontic
treatment techniques.
2. According to the succession stages studied in the
present experiment on laboratory animals, it
was found that the ossification process has a net
coverage tendency on the median palatine
dehiscent suture area; nevertheless, it is placed
under the reserve that our findings are not
directly transferable to human tissue.
3. Enabling the fast and ultra-fast expansion
technique remains accessible, and most often,
after increasing diameters, treatment is
continued with suitable fixed devices.
4. Therefore, structural bone changes obtained
after disjunction and contention, mainly
demonstrates that the therapeutic method
induces permanent changes, offering an
additional guarantee as in terms of maintaining
the stability of the orthodontic treatment
outcome.
5. On the control radiographs taken, it was
observed the split of the medio-sagittal suture,
and the optimal exposure, which highlighted the
changes induced by disjunction, was the axial
angulation.
6. On CT image it was observed medio- sagittal
suture split, recorded on all subjects after
disjunction, specifying that in the case of the
quantitative determination, applied to the rear
portion of the suture, this was recorded at a
level of 30%, compared to the control (CT
scanning technique offering a higher resolution
for transverse dimensions measurements).
115
REFERENCES
1. Ali AM, Sharawy MM, An immunohistochemical study of
collagen types III, VI and IX in rabbit craniomandibular
joint tissues folowing surgical induction of anterior disk
displacement. J Oral Pathol Med 25:78-85, 1996.
2. Al-Qawasmi RA, Hartsifield Jr JK, Everett ET, Flury L,
Liu L, Foroud TM, et al., Genetic predisposition to
external apical root resorption. Am J Orthod Dentofacial
Orthop 123:242-52, 2003.
3. Boboc G., Tratamentul anomaliilor dento-maxilare.
Principii si metode, Edit. Medicala, Bucuresti, 1982.
4. Djasim UM, Hekking-Weijma JM, Wolvius EB, van Neck
JW, van der Wal KG., Rabbits as a model for research
into craniofacial distraction osteogenesis. British Journal
Oral and Maxillofacial Surgery 46:620-4, 2008.
5. Dolce C. Kinniburgh AJ, Dziak R. Immediate early-gene
induction in rat osteoblastic cells after mechanical
deformation. Arch Oral Biol 41:1101-8, 1996.
6. Dorobăț V., Stanciu D., Ortodonţie şi ortopedie dentofacială, Edit. Medicală, Bucureşti, 2009.
7. Garrett BJ, Caruso JM, Rungcharassaeng K, Farrage JR,
Kim JS, Taylor GD., Skeletal effects to the maxilla after
rapid maxillary expansion assessed with cone-beam
computed tomography. Am J Orthod Dentofacial Orthop,
134:8-9, 2008.
8. Glassman AS, Nahigian SJ, Medway JM, Aronowitz HI.,
Conservative surgical orthodontic adult rapid palatal
expansion: sixteen cases. Am J Orthod, 86:207-213, 1984.
9. Hunter CJ, Imler SM, Malaviya P, Nerem RM, Levenston
ME, Mechanical compression alters gene expression and
extracellular matrix synthesis by chondrocytes cultured in
collagen I gels. Biomaterials, 23:1249-59, 2002.
10. Iwasaki LR, Haack JE, Nickel JC, Reinhardt RA, Petro
TM., Human interleukin-1 beta and interleukin-1 receptor
antagonist secretion and velocity of tooth movement.
Arch Oral Biol, 46:185-9, 2001.
11. Liebschner MA., Biomechanical considerations of animal
models used in tissue engineering of bone. Biomaterials,
25:1697-714, 2004.
12. Wang X, Mao JJ. Accelerated chondrogensis of the rabbit
cranial base growth plate upon oscillatory mechanical
stimuli. J Bone Miner Res, 17:1843-50, 2002.